#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

int main()
{
    double price = 0.0;
    int month = 0;
    int day = 0;
    int flag = 0;

    scanf("%lf %d %d %d", &price, &month, &day, &flag);
    if (month == 11 && day == 11)
    {
        price = price * 0.7 - 50.0 * flag;
    }
    else if (month == 12 && day == 12)
    {
        price = price * 0.8 - 50 * flag;
    }
    if (price < 0)
    {
        printf("0.00\n");
    }
    else
    {
        printf("%.2lf\n", price);
    }

    return 0;
}